ACT Preparation / Unit 14 ACT 1324 short lesson, about 20 seconds
Radians
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The idea
A radian is the central angle whose arc equals the radius. A full circle is 2π radians, or 360°, so 180° = π radians.
In practice
90° = π/2; 60° = π/3; 3π/4 = 135°.
Where people slip
Convert by multiplying: degrees times π/180 gives radians, and radians times 180/π gives degrees.
Your place on the trail
Every lesson rests on earlier ones and opens later ones. Tap any to jump.
Builds on
Unlocks
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